ci: expire demo captions and span the whole recording in the contact sheet

Two defects found inspecting the first demonstration of this release:

- A caption stayed on screen until the next one replaced it, so the
  delete-data caption was still displayed over the home view after the
  navigation. Captions now fade and remove at the end of their stated
  duration, so no caption outlives the screen it describes.
- The contact sheet used a fixed 1/2 fps, so a 88s demo only showed its
  first 24s in the review sheet. The sheet rate is now derived from the
  probed duration and a missing sheet fails the build.

scripts/build_release.py

@@ -164,7 +164,13 @@ def main() -> int:
         if len(video_streams) != 1 or video_streams[0].get("codec_name") != "h264" or video_streams[0].get("pix_fmt") != "yuv420p" or video_streams[0].get("width") != 720 or video_streams[0].get("height") != 1280:
             raise SystemExit("Release demo media probe failed")
         contact_sheet = release_dir / f"timmy-talking-turd-{version}-demo-contact-sheet.jpg"
-        run(["ffmpeg", "-y", "-v", "error", "-i", str(demo), "-vf", "fps=1/2,scale=180:-1,tile=4x3:padding=4:margin=4", "-frames:v", "1", str(contact_sheet)], tree)
+        # Span the whole recording: a fixed 1/2 fps sheet only covered the first 24s of a longer demo.
+        demo_duration = float(run(["ffprobe", "-v", "error", "-show_entries", "format=duration", "-of", "csv=p=0", str(demo)], tree, capture=True))
+        if demo_duration <= 0:
+            raise SystemExit("Release demo has no measurable duration")
+        run(["ffmpeg", "-y", "-v", "error", "-i", str(demo), "-vf", f"fps={12 / demo_duration:.6f},scale=180:-1,tile=4x3:padding=4:margin=4", "-frames:v", "1", str(contact_sheet)], tree)
+        if not contact_sheet.exists() or contact_sheet.stat().st_size == 0:
+            raise SystemExit("Release demo contact sheet was not produced")
         run(["npm", "audit", "--audit-level=high"], tree)
         for file in ("app.js", "server.mjs", "service-worker.js", "src/analysis.js", "src/domain.js", "src/draft.js", "src/suggestion.js", "src/followup.js", "src/vision-readiness.js", "src/hermes-agent-service.js", "src/vision-config.js", "src/vision-service.js", "tests/staging.acceptance.mjs"):
             run(["node", "--check", file], tree)

scripts/record_release_demo.mjs

@@ -87,6 +87,16 @@ async function caption(text, duration = 1400) {
     node.animate([{ opacity: 0, transform: 'translateY(-8px)' }, { opacity: 1, transform: 'translateY(0)' }], { duration: 260, fill: 'forwards' });
   }, text);
   await sleep(duration);
+  // A caption must not outlive its stated duration. It used to stay on screen until the next one
+  // replaced it, so a view change left the previous screen's claim hanging over a different screen —
+  // e.g. a delete-data caption sitting on top of the home view.
+  await page.evaluate(() => {
+    const node = document.querySelector('#demo-caption');
+    if (!node) return;
+    node.animate([{ opacity: 1 }, { opacity: 0 }], { duration: 180, fill: 'forwards' });
+    setTimeout(() => node.remove(), 220);
+  });
+  await sleep(220);
 }
 
 async function tap(selector, after = 650) {

tests/release-demo.test.js

@@ -136,3 +136,15 @@ test('release builder refuses to publish without the on-camera delta receipt', a
   assert.match(builder, /"release_delta_visible_on_camera": "passed"/);
   assert.match(builder, /"release_delta": release_delta/);
 });
+
+test('release demo captions expire and the contact sheet spans the whole recording', async () => {
+  const demo = await readFile(demoPath, 'utf8');
+  const builder = await readFile(builderPath, 'utf8');
+
+  // A caption that outlives its stated duration hangs the previous view's claim over the next screen.
+  assert.match(demo, /creates via removal after duration|A caption must not outlive its stated duration/);
+  assert.match(demo, /setTimeout\(\(\) => node\.remove\(\), 220\)/);
+  // The sheet must cover the entire demo, not just its opening.
+  assert.match(builder, /12 \/ demo_duration/);
+  assert.match(builder, /Release demo contact sheet was not produced/);
+});